In industrial applications such as oil or gas refineries, offshore drilling and production platforms, pulp and paper plants, power utilities, oil and gas wells, marine facilities, or any other industry or plant involving vessels, the integrity of vessel nozzle welds or fittings often needs to be tested. In the oil and gas industry, for example, tight environmental and operating regulations exist on emissions from a weld or joint. Furthermore, as there are thousands of welds in each plant, it is in the industry's best interests to minimize the amount of fluid lost from each weld. Testing tools are therefore required to test the integrity and permeability of nozzle welds. Nozzle fittings must also be tested after welding to test and confirm structural strength.
Conventionally, pressure testing of a vessel nozzle is accomplished by pressurizing the entire vessel. Such testing is time consuming, expensive, and can create potential hazards. In addition, welding operations utilized to join nozzles or branch connections to existing vessels may be performed in the presence of combustible or otherwise harmful materials or vapors which are present within the vessel.
These problems are well known, and tools for solving these problems exist in the prior art. For example, U.S. Pat. No. 6,675,634 to Berneski et al. discloses a tool and method for isolating and testing a connection, such as a welded connection, which interconnects the wall of a tank, vessel, or pipe to a branch pipe or nozzle. This tool uses an inner subassembly and an outer assembly to form a fluid-tight chamber around a nozzle connection to a vessel. The inner subassembly extends around the internal end of the nozzle connection and forms a fluid-tight seal with the inner surface of the vessel. The outer subassembly forms a fluid-tight seal with an external flange of the nozzle. When the tool is installed and tightened, a resilient face seal of the inner subassembly is compressed into engagement with the inner surface of the vessel. The nozzle connection is completely enclosed within the subassembly and is thus isolated from the remainder of the vessel.
The problem with the tool of the '634 patent to Berneski is that the resilient seal does not easily conform to surface irregularities on the inner surface of the vessel. Further, elastic stretching of the tool during pressure testing may move the inner subassembly slightly away from the vessel wall, breaking the seal and defeating the test. These deficiencies may be offset by using “torquing” methods to set the seal in place. However, this results in the introduction of concentrated stresses in the vessel wall in contact with the narrow seal. This may create a future weak spot.
Besides sealing deficiencies, the '634 patent to Berneski also fails to teach a tool that can adapt to variations in nozzle configuration. For example, the tool cannot adapt to angular variations between the external flange of the nozzle and the inner surface of the vessel. This lack of adaptability means that other tools must be used, increasing the costs of maintaining and testing nozzles.